Transcript Ch 13.1 Notes

Electrical Circuits
CHAPTER 13
13.1: ELECTRICAL CIRCUITS
•
Objectives
– Explain how electrical energy is
supplied to devices in a circuit.
– Use electrical symbols to draw
simple circuit diagrams.
– Distinguish between open and
closed circuits.
ELECTRICITY
 What
is electricity?
 Electricity
usually means the flow of
electric current in wires, motors, light
bulbs, and other inventions.
Its what makes an electric motor or
electric stove heat up.
Almost always invisible.
Comes from the motion of electrons or
other charged particles.
 Electric
Current
Similar to a current of water, but not
visible because it flows inside solid metal
wires.
Can carry energy and do work, just as a
current of water.
Ex. A water
wheel – uses the
force of flowing
water to run
machines.
 Electricity
can be powerful and
dangerous!
Electric
currents carry a great deal of
energy.
Ex. An electric saw
An electric motor the size of a basketball
can do as much work as five big horses or
fifteen strong people!
ELECTRIC CIRCUITS
 An electric circuit is a complete path through
which electricity travels.
 Ex.
Electric toaster
 Wires
in electric currents are similar to pipes
and hoses that carry water.
 Difference
is that you cannot get electricity to
leave a wire the way water leaves a pipe.

Examples of natural circuits:
 The nerves in your body are an
electrical circuit that carries
messages from your brain to your
muscles.
 The tail of an electric eel makes a
circuit when it stuns a fish with a
jolt of electricity.
 The Earth makes a gigantic circuit
when lightning carries electric
current between the clouds and
the ground.
CIRCUIT DIAGRAMS AND ELECTRICAL SYMBOLS

Circuit diagrams
 Circuits
are made up of wires and electrical
parts such as batteries, light bulbs, motors and
switches.
 Electrical drawings are called circuit diagrams.
 Symbols are used to represent each part of the
circuit in a circuit diagram and are standard.
 A resistor is an electrical device that uses the
energy carried by electric current in a specific
way.
OPEN AND CLOSED CIRCUITS

Batteries
 All
electrical currents must have a source of
energy.
One way to turn off a device is to stop the
current by “breaking” the circuit.
 Electric current can only flow when there is a
complete and unbroken path.
 A circuit with no breaks is called a closed
circuit.
 A circuit with any break is an open circuit.


Switches
 Switches
are used to turn electricity on and off.
 Flipping a switch to the on position creates an
open circuit by making a break in the wire.
 A light bulb burns out when the thin wire that
glows inside it breaks, breaking the circuit.
DIAGRAM 13.5 PAGE 301